@misc{oai:repo.qst.go.jp:00081422,
 author = {Ihara, Tomokazu and Noguchi, Miho and 岡部, 弘基 and Yokoya, Akinari and Ihara, Tomokazu and Noguchi, Miho and Yokoya, Akinari},
 month = {Dec},
 note = {Introduction
 Mammalian fibroblast cells undergo cellular senescence by high dose X-ray irradiation. Although the senescence is distinct from those caused by telomere shortening, both exhibit similar characteristic such as being irreversible cell cycle arrest and releasing bioactive substances that promote carcinogenesis or induce further senescence in surrounding cells. The evidence suggests that intracellular physiological reaction of senescent cells might be different from those of normal cells. We focused on intracellular temperature, as one of physicochemical index to evaluate the physiological changes in senescent cells. ATP molecules consumed in various reactions transfer energy to conjugated reactions, and then some of the energy might be converted to heat which possibly raises intracellular temperature. To clarify whether cellular temperature correlated with radiation-induced senescence, we performed measurements of the cellular temperature by introducing a thermoprobe, Cellular Thermoprobe for Fluorescence Ratio, into immortalized human fibroblast cells.

Method
The cells were exposed to 20 Gy X-rays. More than 90% of cells were confirmed undergoing senescence on eighth day after irradiation by SA-β-gal staining method. The thrmoprobe was introduced into the cultured cells, and then the ratio of red and green fluorescence intensity was determined with microscopic fluorescent images. Intracellular ATP levels was also measured by a luciferin-luciferase method.

Result and Discussion
The temperature of senescent cells was about 4°C higher than that of normal cells. This suggest that heat release reaction may be increasing in senescent cells. We also found a higher level of intracellular ATP in senescent cells than that in normal cells. This may be due to reduced ATP consumption with the arrest of the cell cycle. From these observations, it is inferred that deconjugation in mitochondria in senescent cells results in temperature evaluation without any ATP consumption., The 3rd International Forum on Quantum Metrology and Sensing},
 title = {X-ray induced cell cycle arrest and raises the cellular temperature},
 year = {2020}
}